Tensiometer control



M y 1941- s. P. LESSMANN' 2,242,353

TENSIOMETER CONTROL Filed Aug. 13, 1938 3 Sheets-Sheet 1 mukmmw FQ NR n :5: In

INVENTOR RM E RQ V Ger/20rd P Lss/vzazm.

y 1941- G. BLESSMANN 2, ,3

' TENSIOMETER CONTROL I Filed Aug. 13, 1938 s Sheets-Sheet 2 INVENTOR VyITN ESSESZ ,Pessmahfl. I Q! 4 MW A bRNEY Patented May 20,1941

umrsp 'STAT.ES I PA NT mes msroamrsa CONTROL Gerhard P.- Forest Hills, 2a., assignor. to Westinghouse- -Electrlc & Manufacturing vtioinpany, East Pittsburgh, Pa., a

. of Pennsylvania corporation Application August 13, 1938, Serial No. 224,724

. Claims.

My invention relates, generally, to devices for tensioning a length of material as it passes between adjacent work devices and, more particuwhich shall function to accurately regulate the tension on a strip of material as it passes between two adjacent work devices and which shall larly. to a control system for a fluid-pressure actuated strip tensioning device.

In the manufacture ofsheet steel, it has become the practice to pass the steel in the form of a strip through a series oi sets of reducing rolls simultaneously and to subject the strip to tension as it passes between adjacent roll stands by causes an idling roller to bear against the strip to deflect the strip from the normal between adjacent roll stands.

Fluid-pressure operated pistons have been used for actuating strip tensioning devices and have pass line been very successful because of the low inertia,

flexibility, ease of regulation and wide range of regulation of the systems using fluid pressureas an operating medium. Such a fluid-pressure opoccasional sticking of the control solenoid core hindered the proper operation of the valves Another defect in these valves has been that the valve faces have been damaged bythe'sudden closing of the valve under the great force applied by the control magnet.

In the operation of such fluid-pressure actuated strip tensioning systems as I have described in my heretofore referred to copending patent application, it has been. found that unusually function to reduce the amount of strip breakage by relieving tension surges on the strip.

Another object of the invention is to provide I an improved electromagnetically adjustable fluid-pressure-regulating reducing valve which shall functionto accurately and emciently maintain a predetermined fluid pressure in-a fluid- I pressure-actuated strip tensioning system.

A further object of the invention is to provide a fluid valve which shall be so constructed as to automatically protect its valve surfaces from damage due to sudden closureoi the valve with great force.

Still another object of the invention is to provide a relief valve system for a fluid-pressure actuated strip tensioning device which shall function to relieve excess pressures in the system regardless of the value of the normal pressure act-- ing in the system.

These and other objects and advantages of the invention will be apparent from the following detailed description taken in connection with the accompanying drawings, in which:

Figure 1 is a diagrammatic representation of astrip tension control system embodying the principal features of my'invention.

Fig. 2 is an elevational view in section 013 the pressure regulating valve or Fig. i.

. Fig. 3 is an -'elevational view in section of the' relief valve of Fig. 1; and

4 is a view of a section of a modification of the core structure of the solenoid of the regulating valve of Fig. 2.

high tension surgessometimes occur, particularly during the periods of acceleration and deceleration of the mill. These high tension surges are due to the sudden take-up of the slack in the strip between roll stands which tends to force the fluid-pressure operated piston back in the cylinder. It will be seen that, if the pressure in the cylinder could bedessened when these tension surges occur, the severity of the surges would be lessened and breakage of the strip due to these tension surges could be eliminated.

An'object of my invention; therefore, is to pro vide a fluid-pressure operated tensioning'system limits.

In a general aspect, the invention comprises a 'tensioning device iii which acts to apply a tensionto a strip of material, such as sheet steel i2, as it passes between adjacent reducing roll stands or similar work devices I 6 and IS in the direction indicated by the arrow. A regulator it, responsive to the degree of deflectionof the strip 12, controls thespeed of the driving motor H for the rolls'of roll stand it to maintain the deflections of the strip within predetermined The tensioning device ill ,is actuated by a fluidpressure operated piston and cylinder device v20, the tension applied to the strip I! by the ten. sioning device l0 being a function of the fluid pressure acting on the piston and cylinder device 20. An adjustable pressure regulating reduction valve 22 is connected between any suitable fluid- 1 pressure source, as indicated, and the cylinder A checlr' valve 24 is connected in the conduit between the regulating valve 22- and the piston and cylinder device 28 to prevent reverse flow ofpressure fluid from the piston and cylinder device 28 to the regulating valve 22 upon the occurrence of sudden tension surges which tend to cause the piston to compress the pressure fluid in the cylin-.

der. A compensated relief valve 28 having a diaphragm actuated valve is connected to permit its detailed description of the structure and operation of the fluid-pressure regulating valve 22,

diaphragm to be affected by the regulated fluid t v 82 is secured to the upper diaphragm clamp 88.

pressure on one 'side and the fluid pressure acting on the piston on the other side so that the relief valve will open to relieve tension surges when such surges cause a predetermined increase of pressure in the cylinder over the rgulated pressure.

As shown in Fig. 2, the pressure regulating valve 22 "comprises a valve 28 disposed between inlet and outlet ports 30 and 22 respectively. The valve 28 is connected to be actuated by a diaphragm 34,- on which the regulated pressure acts to close the valve through a spring 88-, a

regulatable biasing spring 88, which tends to move the valve to open position, and a solenoid 40 which partially counteracts the pressure of the spring 38. The air gap 4I of the solenoid is constructed to provide a self-centering actionon the solenoid cores to prevent sluggish action of the valve due to the sticking of the .core. An alternative form of self-centering core is shown in Fig. 4. '3

As shown in Fig. 3, the relief valve 28 comprises'a valve 42 disposed between inlet andoutlet ports 44 and 46, respectively, and actuated by a diaphragm 48. The diaphragm is acted upon on one side by the pressure existing in the cylinder of the tensioning device actuating means and on the other side by a spring 50 and the regulated pressure 'from the regulating valve 28 which is introduced into the chamber 52 through the Referring to the drawings for a more detailed description of the invention, in Fig. 1, the tensioning device I0 comprises a bell crank 53 pivotalLv mounted upon a support 88 and having an arm 58 upon which there is rotatably' mounted an idling roller 80. Another arm 82 of the bell crank 53 is acted upon by a piston 84, which is actuated by fluid pressure in a cylinder 88. This general arrangement of fluid-pressure operated tensioning device will maintain a tension upon the strip I2 dependent upon the fluid pressure acting in the cylinder 88 and will govern the speed of the motor II which drives the producing roll I8 by means of a regulator II which acts to control the current in the fleld winding 68 of the motor n to' maintain the deflection of the strip I2 within predetermined limits. This general arrangement of the tensioning device and regulator is disclosed in my above referred to patent, to which reference is made for a more detailed description of the apparatus and its operation.

the valve comprises a valve chamber 18 having openings", 80 and 82. A valve support 84 is inserted into the opening 82 and secured to the valve chamber 18 in any suitable manner, such as byscrew threads as shown. A valve seat 88 is screw threaded intothe valve support 84 and has the valve 28 cooperating therewith. The diaphragm 34 is secured between upper and lower diaphragm clamps 88 and 88 in any suitable manner as by screw threaded engagement between these two members, and a spring cage The valve stem 84 extends from the valve 28 I through an opening in the valve cage 82 and has screw threaded engagement with the valve nut .88. The spring 38 is disposed betweenthe valve nut 88 and the spring cage 82.

The diaphragm 84 has its outer edge clamped between the valve chamber I8 and a spring housing 88. An adjustable spring support sleeve I08 is screw threaded into the spring housing 88 and a spring 88 is disposed between the sleeve I00 and the lower diaphragm clamp 80 to bias the valve 28 toward open position. Q

The housing I02 of the solenoid 40 is secured I to an extension of the, spring housing 88 and comprises upper and lower portions which are suitably clamped together, as shown. A fixed centralsolenoid core member I08 is secured to the lower section of the solenoid housing and a movable solenoid core member I08 is disposed adjacent the core member I08, cooperating therewith as a part of the magnetic circuit of the solenoid 40. The movable core section I08 is connected to the valve 28 through a stem IIO,

a coupling H2 and a stem I I4, which has screw able solenoid core section I08, the stem IIO, the

threaded engagement with the lower diaphragm ring member Hi, the air gap between the ring member IIS and the housing I02, and the solenoid housing I02. A sleeve I20 of non-magnetic material, such as brass, is disposed'around and spaced from the movable solenoid core sec- In, order to maintain a constant pressure in able conduit 12 through a check valve 24 and a a conduit 14 to the cylinder 68. 7 Referring to Fig. 2 of the drawings for a more tion I08 and the solenoid core I22 is disposed around the sleeve I20.,

The adjacent cooperating faces of the solenoid core section' I06 and I08 are cone shaped in form so as to provide a concentration of the magnetic flux at the apex of the cones to thus provide a centering force to keep the movable core section I08 centered in the sleeve I28, thus preventing sluggish operation of the valve due to frictional engagement of the movable core section I08 with the sleeve I20.

An alternative form of the cone sections ,I88 .and I08 is shown in Fig. 4 where the oppositely disposed faces of the core sections are formed in thevshape of V-shaped rings having their apexes centered and oppositely disposed. This form of core face will perform the desired centering function, and it will also permit the flow of a greater amount of flux through the air gap 4| than can be providedby the form of core section face shown in Fig. 2.

- The pull of the solenoid 40 will provide a downward force acting againstthe'spring 38, thus diminishing the amount of bias tending to move closed position.

amount.

acting in the valve chamber l8 against thediaphragm 88 tending to move the valve 28 to At the same time, the comaacasse the function of cushioning the seating tforce applied to the valve 82, thus protecting the valve pression of the spring 88 minus the force exerted against the spring 88 by the solenoid 88 will be acting to move the valve 28 to open position; Thus, the valve 28 will be moved to open position to admit pressure fluid from the fluid-pressure source into the cylinder 88 until the pressure in the cylinder 88 and in the chamber 18 is such that this'action on the diaphragm 88 will overcomev the spring pressure upon the diaphragm and close the valve 28. It will be seen that any decrease in pressure in the cylinder 88 and the chamber I8 will againcause the valve 28 to opento bring the pressure upto. the desired The amout of pressure acting upon the cylinder 88 is thus determined by the amount ,of tension applied to the diaphragm 88 by the suitable adjustment of the'spring support sleeve 82 and itsseat I88 from damage which might result from too great a seating force being applied thereto. Y

A housing 82 is suitably secured to the valve chamber I88, the diaphragm 88 being clamped between said housing and chamber. .A spring ,88 bears against the lower valve clamp I82 and against the housing 82. The housing 82 has an opening 88-to which the fluid conduit I28 is connected. The fluid conduit I28 hereinbefore referred to is suitably connected to the opening 88 in the housing I88 and a suitable conduit I88.

opening to the atmosphere, is connected with the piston 88 andthe cylinder 88, exceeds the regulated pressure applied to the lower sideof sure from the cylinder '88 from being applied t6 the regulated valve 22. Thus, therelief valve I88 and the degree of energization of the solenoid to the valve 28 and its seat 88 by any pressure surge that might occur in the chamber 18 or any excess forces that might be applied by the solenoid 88 due to surges in the energizing current of the solenoid. I

In order to relieve excess tension surgesin the strip I2, which might be caused by sudden variations in the speeds of the rollsoithe mill stands I8 and I8 or sudden variations in the v hardness of the strip, or any other condition that would cause sudden decrease in the amount of slack in the strip I2 between the roll stands- I8 and I8, the relief valve 28 is connected by a suitable conduit I28 to the cylinder 88 to relieve 28 will not operate at a definite pressure, but will operate at -a definite excess of pressure over the regulated pressure which the regulating valve 22 is adpusted to deliver to the cylinder 88. I! it is desired, the relief valve 28 may be so con- ;structed as to provide an adjustment for the spring 88' to provide thereby an adjustment of the excess pressure to which therelief valve-is responsive.

In the operation of thesystem, it will be seen that the regulating valve 22 will provide a constant predetermined pressure in' the cylinder 88,

as determined by the adjustment of the rheostat I28, and this constant pressure will act through the tcnsioning device I8 and the regulating device I 8 for the motor II to maintain a constant deflection of the strip I2 and the constant tension on the strip I2.. If now, for any reason, there shouldbe a sudden decrease in the deflection of the strip I2 'due to a decrease in the amount of slack in the strip I2 between the roll stands I8 and I8, the piston 88 will be forced up in the excess pressures in the cylinder 88 which would be caused by sudden decreases in the length of the strip I2 between the roll stands I8v and I8, forcing the pistons 88 upward in the cylinder 88. Th relief valve 28 is also connected to the valve chamber I8 through the opening 88 by means of;

a suitable conduit I28 to provide pressure compensation for the relief valve 28, as hereinafter more fully explained.

Referring to Fig. 3for e morefdetailedpde scription of the relief valve 28, the valve chamber 5 I88, similar to the valve chamber I8 of the pressure regulating valve 22, has an opening I32 closed by any suitable means, such as a cap I88 and has a valve support I38 inserted therein. A valve seat I38 is provided in the valve support I88 and avalve 82 cooperates therewith. A'- diaphragm 88 is secured between upper and lower diaphragm clamps I88 and I82, and a' spring cage I43 is secured to the upper diaphragm iii) cylinder '88 causing a sudden increase in the pressure in cylinder 88 and a sudden increase in the tension on the strip I 2. This increase in pressure in the cylinder 88 will close the check valve 28, preventing flow of pressure fluid in the reverse direction toward the regulating valve 22 and if this resulting pressure in the cylinder 88 is suificiently in excess of the regulating pressure provided by the regulating valve 22, the relief,

' lating' valve 22 to provide the desired-constant pressure in the cylinder 88. This increase'in pressure will not operate the relief valve 28 for thereason that this regulated pressure is applied to the lower side of the diaphragm 88 through I the conduit I28 as well as to the upper side of the diaphragm 88 through the conduit I28, and the relief valve 28 will thus be compensated for any,

regulated changes in fluid pressure, but will-still relieve excess pressure generated in the cylinder 66 by sudden decreases in the deflection of the strip 12 to thus relieve tension surges in the strip I2. I

It will be seen that I have provided a control system for a fluid-pressure actuated strip tensioning device which will function to efliciently and accurately maintain a predetermined tension upon the strip during normal conditions, which will function to relieve excess tensions on the strip by means of a relief valve which may be adjusted to provide any desired normal tension on the strip and which will automatically compensate the relief valves for change in regulated tension on the strip so that the relief valve will only act upon sudden increases of tension above the regulated tension on the-strip.

In compliance with the requirements of the patent statutes, I have shown and described herein the preferred embodiments of my invention. It is to be understood, however, that the invention is not limited to the precise constructions shownand described but is capable of modification by one skilled in the art, the embodiments herein shown being merely illustrative of the principles of my invention.

' 2. In a control system for a fluid-pressure ac-- tuated strip tensioning device, an adjustable pressure regulating valve for maintaining a predetermined normal pressure on the tensioning device, a pressure actuated relief valve for relieving excess fluid pressure on the tensioning device and means for changing the relief valve operating pressure in accordance with changes in the normal pressure provided by said regulating valve for the tensioning device.

3. In a control system for a fluid-pressure operated piston-actuated strip tensioning device, an adjustable pressure regulating valve for maintaining a predetermined normal pressure on the actuating piston, a pressure operated relief valve for relieving excess fluid pressure on the piston,

and means controlled by the regulated normal pressure for the actuating piston for varying the relief valve operating pressure in accordance with the adjusted variations of the regulated normal pressure.

4. In a system for maintaining a predetermined normaltension on a strip of material as it passes between adjacent work devices, an idling roller, means including a fluid-pressure actuated pistonfor causing said roller to deflect the strip from its normal pass line between theiwork devicesto thus tension the strip, an adjustable pressure regulating valve for maintaining a preenergization of said electromagnet to thereby vary the fluid pressure applied to the tensioning determined normal pressure on the actuating piston, a pressure operated relief valve for relieving excess fluid pressure on the piston, and means controlled by the regulated normal pressure for the actuating piston for varying the relief valve operating pressure in accordance with the adjusted variations of the regulated normal pressure.

device through said regulating valve thus varying the tension applied to the strip by said tensioning device; a relief valve connected to relieve excess fluid pressure on the tensioning device and means for varying the operating pressure of said relief valve in accordance with variations in the normal pressure maintained on the tensioning device by said regulating valve.

6. In a fluid-pressure regulating reduction valve for maintaining a predetermined selectively adjustable fluid pressure on a fluid-pressure actuated strip tensioning device, a valve,-pressure responsive means for biasing said valve toward opposing faces of such contour as to concentrate the magnetic flux flowing therebetween substan-' tially in the line of movement of the movable core to thereby conflne the movement of the movable core to the desired axial movement.

7. In fluid-pressure regulating reduction valve for maintaining a predetermined selectively adjustable fluid pressure on a fluid-pressure actuated strip tensioningdevice a valve, pressure responsive means for biasing said valve toward the closed position, means for biasing said valve toward open position and a selectively adjustable continuously energized solenoid having its core connected to continuously bias said valve to the closed position with a selectively adjustable force to thereby provide a selectively adjustable net valve biasing force, said solenoid comprising a winding disposed upon a sleeve, 8. fixed core and a movable core disposed in cooperative relationship within said sleeve as a part of the magnetic circuit of the solenoid, said cores having opposing able core to the desired axial movement and preventing contact of the movable core with said sleeve. 4

8. In a fluid-pressure regulating reduction valve for maintaining a predetermined adjustable fluid-pressure on a fluid-pressure actuated strip tensioning device, a valve, pressure responsive means for biasing said valve toward the ,closed position, means for biasing said valve toward open position and a continuously energized solenoid having its core connected to bias said valve to the closed position, said solenoid comprising a winding disposed upon a sleeve, a yoke of magnetic 'material disposed about said coil and having an opening coaxialwith said ber toward closed position with a force proportional to the regulated pressure provided by said sleeve, a fixed core disposed within said sleeve and secured to said yoke, a movable core disposed within said sleeve in cooperative relation with said fixed core, said movable core being slidable axiallyof but spaced from said sleeve, a stem of magnetic material secured to said movable core and extending through said opening in said yoke, a plate of magnetic material secured to said stem overlying the opening in said yoke and so disposed with respect to said yoke as to form-a part of the magnetic path of said solenoid, said fixed and movable cores having opposed faces so shaped as to cause a concentration of the magnetic flux flowing therebetween substantially in the axial line of said solenoid to thereby confine the movement of the movable core to the-desired axial movement and preventing contact of the movable core with said sleeve. v

9. In a control system for a fluid-pressure actuated strip tensioning device, an adjustable pressure regulating valve for maintaining a predetermined normal pressure on the tensioning device, a pressure relief valve for relieving excess fluid pressure on the tensioning device, said relief valve comprising a valve member, a first means biasing said valve member toward closed position, a second means biasing said valve memregulating valve, and means biasing. said valve member toward open position with a force proportional to the fluid pressure acting on the tensioning device.

10. In a control system for a fluid-pressure operated piston-actuated tensioning device, an adjustable fluid-pressure regulating valve for providing a predetermined selectable fluid pressure for the actuating piston, a check valve for preventing fluid flow from the piston toward said regulating valve, a pressure relief valve for relieving excess fluid pressure on the tensioning device, said relief valve comprising a first chamber, a valve member controlling an outlet from said first chamber,.a second chamber, an imperforate flexible diaphragm forming a common wall between said first and second chambers,

means connecting said valve member for operation by said diaphragm, means biasing said valve toward closed position,'-means connecting said first chamber to be affected by the fluid pressure acting on the piston and means connecting said second chamber to be affected by the fluid pressure provided by said regulating valve.

GERHARD P. LESSMANN. 

